Plastic mailbox



FIG. 1 is a perspective view showing the new design; the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is a front elevational view of the present invention; the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 3 is a right side elevational view of the present invention; the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 4 is a top plan view of the present invention; the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 5 is a rear elevational view of the present invention; the broken lines are for illustrative purposes only and form no part of the claimed design; and,

FIG. 6 is a left side elevational view of the present invention; the broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a plastic mailbox, as shown and described. 